Air conditioning apparatus having condensation preventing means



Dem 6, 1966 c, c. HERB ETAL 33$QA-35 AIR CONDITIONING APPARATUS HAVING CONDENSATION PREVENTING MEANS Filed Aug. 25, 1965 INVENTORS. CA C. HERB. BY [M F. BRYANS.

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United States Patent 3,289,435 AIR CONDITIONING APPARATUS HAVING CONDENSATION PREVENTING MEANS Carl C. Herb, Syracuse, and David F. Bryans, Cazenovia,

N.Y., assignors to Carrier Corporation, Syracuse, N.Y.,

a corporation of Delaware Filed Aug. 25, 1965, Ser. No. 482,438 5 Claims. (Cl. 62--272) This invention relates to an air conditioning unit ineluding means for controlling the condensing of moisture on the unit and, more particularly, to an air conditioning unit including means for substantially preventing the passage of condensate onto a portion of the unit and the formation of condensate on this portion of the unit.

Dripping of moisture has been a common problem in various types of air conditioning installations. Where it is possible to do so, drain pans for catching dripping moisture may be provided but are often not completely effective in preventing dripping from an air conditioning unit. For example, a drain pan cannot conveniently extend under the portion of a chilled air outlet projecting through a building partition, but condensate may appear about the outlet portion of the unit and ultimately wet the partition, which is obviously undesirable. While insulation can prevent the formation of condensate on a surface, condensate from an adjacent portion of the surface may wet the insulation. Such insulation is often not suited for factory application on a packaged air conditioning unit, such as a fan coil unit, and must be applied in the field thus adding to installation time and cost.

It is a primary object of this invention to provide a new and improved air conditioning unit and, more particularly, to control condensate and the formation of condensate on the unit. More specifically, it is an object of the invention to substantially prevent the passage of condensate from a first portion of the unit, which is below the dew point, to an adjacent second portion, and for preventing suflicient conduction of heat between the first portion and the second portion to prevent the formation of condensate on the second portion. A related object is provision for guiding condensate on the first portion to a desired portion of the surface away from the second portion.

These and other objects and advantages of the inven tion will be apparent from the following description and the accompanying drawing in which:

FIGURE 1 is a perspective view of an air conditioning unit embodying features of the invention; and

FIGURE 2 is an enlarged, fragmentary sectional view taken generally along the line IIII in FIGURE 1.

Referring to FIGURE 1 of the drawings, an air con ditioning unit, and more particularly, a fan coil unit includes a casing 12 usually of galvanized iron or steel or other metal which readily conducts heat. The casing 12 forms a passage for air and contains a finned coil heat exchanger assembly 13 in the passage for cooling the air forced by a pair of blowers 14 through the casing passage and coil assembly and out a casing outlet portion 15. Condensate collecting on the casing 12 drips into a drain pan 17 below the casing and then passes through a drain connection 18. The drain pan 17 has a front wall 19 spaced rearwardly of the outlet 15 so that a duct may be telescoped over the casing 12 about the outlet, or the portion of the casing about the outlet may extend into a cutout in a building partition. The fan coil unit may be mounted in any suitable manner, for example, by hangers,

(not shown) extending through slots 20 in flanges projecting from a top wall 21 of the casing 12 and past opposite side walls 22 of the casing.

The finned coil assembly 13 has opposed tube sheets 23, only one tube sheet being shown. The tube sheets mount finned tubes 24 connected in fluid circuit through nipples 25 with a chilled water line (not shown) for the circulation of chilled water through the tubes. Opposed flanges 26 (FIGURE 2) of the tube sheets 23 are tightly clamped about opposed flanges 27 of the adjacent side wall 22 to provide a seal substantially preventing escape of air from the casing 12 between the tube sheet 23 and side wall 22, and resulting in substantial conduction of heat between the chilled tube sheet and the side wall. During operation of the fan coil unit the chilled water passing through the tubes 24 usually maintains the tube sheets 23 and the adjacent side walls 22 below the dew point of ambient atmosphere, resulting in condensate from the ambient atmosphere forming on the side walls and dripping into the drain pan 17 below the casing.

Since the drain pan 17 is spaced rearwardly of the front of the casing, it is desirable that condensate be prevented on this part of the casing. To this end, one or more apertures, preferably in the form of elongated slots 32, are provided in each side wall 22 between a first or main side wall portion 33 including the flanges 27 engaging the tube sheet 23, and a front or second portion 34 of the side wall 22 adjacent the outlet 15, in order to reduce the heat conduction therebetween. The temperature of the ambient atmosphere, which is normally above its dew point, maintains the side wall front portions 34 above the dew point and prevents condensation forming thereon.

Each slot 32 is preferably upwardly inclined slightly off true vertical from the main portion 33 toward the front portion 34 of the side wall 22 so that an edge 35 of each slot adjacent the main portion 33 is in the flow path of the condensate downwardly and away from the front portion 34. The surface tension of the condensate prevents the condensate from crossing these slot edges and spaning the slot and passing onto the outlet portion 34. A plurality of slots 32 are preferably provided in each side wall 22, for example, a lower slot 32a and an upper slot 32b. The upper end of the lower slot 32a overlaps and is horizontally spaced toward the front portion 34 from the bottom end of the upper slot 32b, to increase the length of the path of heat conduction 36 between the slots 32a and 32b and therefore reduce heat transfer between the front portion 34 and main portion 33 of the wall 22, and to provide adequate structural strength between the mounting and main portions of the wall. The upper end of the upper slot 32b is positioned as close as practical to an upper edge 37 of the side wall at the outlet 15 to avoid substantially weakening the edge 37 while still substantially preventing condensate on the upper part of the side wall front portion 34. The bottom end of the lower slot 32a is positioned above the drain pan 17 rearwardly of the drain pan front wall 19 so that the condensate flowing on the main portion 33 of the side wall 22 along the rear edge 35 of the lower slot 32a is guided into the drain pan 17.

The inner surface of the casing side walls 22 are covered with a suitable insulation 38 preferably adhesively secured to the inner surfaces, thus effectively preventing the formation of condensate within the casing and cooling of the side wall front portions 34 by the chilled air. The slots 32 facilitate escape of solvent in the adhesive bonding the insulation 38 to the side walls 22.

In the copending application of Darwin G. Traver, Serial No. 482,422, filed August 25, 1965, there is disclosed an air conditioning unit provided with means to prevent conduction of heat through a wall surface suflicient to prevent formation of condensate thereon.

While a preferred embodiment of the invention has been described and illustrated, it should be understood that the invention is not limited thereto but may be other- 3 Wise embodied within the scope of the following claims.

We claim:

1. In an air conditioning unit, the combination of means including a casing forming a passage for air, said casing having a wall with surface on which droplets of condensate may form when the surface temperature is below the dew point of ambient atmosphere, said surface including first and second portions, said first portion being below the dew point during operation of the unit, means for supplying air through said passage, means adapted to cool the air passing through said passage, and at least one generally upright slot in said wall for substantially preventing conduction of heat through said wall between said portions sufiicient to permit formation of condensate on said second portion and for substantially preventing any condensate on said first portion from passing onto said second portion.

2. The unit of claim 1 in which said slot is upwardly inclined from said first portion toward said second portion to guide condensate passing downwardly on said first portion away from said second portion.

3. The unit of claim 4 in which said aperture means includes a plurality of said slots with the upper portion of a lower one of said slots overlapping and being horizontally spaced toward said second portion from the lower portion of an upper one of said slots to guide condensate passing downwardly on said first portion away from said second portion.

4. In an air conditioning unit, the combination comprising a casing forming a passage for air, said casing including a side wall having an outer surface and first and second portions adjacent each other, means for passing the air through the casing passage, heat exchange means within said casing adapted to cool the air passing through the casing passage and maintain a temperature below the dew point of ambient atmosphere, means associating first portion of said wall in heat exchange relationship with said heat exchange means thus maintaining said first portion below said dew point when said heat exchange means is below said dew point, whereby moisture may condense on said first portion of said outer surface, and means for substantially preventing conduction of heat through said wall between said portions sufiicient to permit formation of condensate on said second portion and for substantially preventing any condensate on said first portion from passing to said second portion, the last said means defining a plurality of slots in said wall between said first and second portions, said slots being upwardly inclined from said first portion toward said second portion with the upper portion of a lower one of said slots overlapping and horizontally spaced toward said second portion from the lower portion of an upper one of slots to guide condensate passing downwardly on said first portion away from said second portion.

5. The unit of claim 4 in which said casing has an outlet portion for the cooled air in said casing passage, said outlet portion being adjacent said second portion of said wall, a drain pan under said casing for receiving condensate from said wall, said drain pan being spaced inwardly from said outlet poition, said heat exchange means includes a coil assembly in said heat exchange relationship with said wall, the lower portion of said lower slot being directly above said drain pan for guiding con-, densate on said first portion into said drain pan, and thermal insulation on a surface of said wall opposite the first said surface and extending across said slots for substantially preventing said chilled air from cooling the outer surface of said second portion and substantially preventing the passage of air through said slots.

References Cited by the Examiner UNITED STATES PATENTS 1,870,460 8/1932 Lambert 6293 2,740,268 4/1956 Jones 6293 WILLIAM J. WYE, Primary Examiner. 

1. IN AN AIR CONDITIONING UNIT, THE COMBINATION OF MEANS INCLUDING A CASING FORMING A PASSAGE FOR AIR, SAID CASING HAVING A WALL WITH SURFACE ON WHICH DROPLETS OF CONDENSATE MAY FORM WHEN THE SURFACE TEMPERATURE IS BELOW THE DEW POINT OF AMBIENT ATMOSPHERE, SAID SURFACE INCLUDING FIRST AND SECOND PORTIONS, SAID FIRST PORTION BEING BELOW THE DEW POINT DURING OPERATION OF THE UNIT, MEANS FOR SUPPLYING AIR THROUGH SAID PASSAGE, MEANS ADAPTED TO COOL THE AIR PASSING THROUGH SAID PASSAGE, AND AT LEAST ONE GENERALLY UPRIGHT SLOT IN SAID WALL FOR SUBSTANTIALLY PREVENTING CONDUCTION OF HEAT THROUGH SAID WALL BETWEEN SAID PORTIONS SUFFICIENT TO PERMIT FORMATION OF CONDENSATE ON SAID SECOND PORTION AND FOR SUBSTANTIALLY PREVENTING ANY CONDENSATE ON SAID FIRST PORTION FROM PASSING ONTO SAID SECOND PORTION. 